# 2 Not Firing Properly?

[JungleJustice]

So, I got the bike (1980 GS1100 E) running again yesterday after all of the resto work, but there is a persisting rough running and the #2 pipe on the new exhaust isn't turning like the others...

Pet-cock rebuild? (Cylinder # 2 has the vacuum-line on it, correct)? It's either sucking air in somehow and running lean, or it is sucking in extra fuel to that hole and running rich - me thinks!?

History:

Bike sat in a shed for 3 years. I rescued it, changed the oil, plugs and battery - flushed in some fresh fuel, serviced the carbs and it fired right up! I rode it around for a few weeks and it ran great ( a bit rough on idle and hard to warm a bit), but pretty smooth on full-throttle! Knew that it just needed some love.

Then we broke it down for some major work! One interesting thing that I spotted right away when we removed the standard exhausts, was that the #2 and #3 pipes were both black and sooty inside, whereas on the #1 and #4 holes, the pipes were black at the inlet for about an inch or so and then a nice tan-white colour all of the way down inside the header from there as far as I could see with a flash-light...

My first thought then was a bad coil (for #2 and #3...)!?

Engine/fuel/ignition/running-related changes and updates made since then;

*Brand new choke cable
*Brand new Dyna green coils.
*Brand new Dyna DW-800 8mm plug-wires.
*Re-checked the gap on the plugs.
*Brand new airbox intake-boots.
*Brand new air filter.
*Brand new V&H 4-into-1 street pipes.
*Checked the ignition, lubed the pivot-points on the advance and made sure it all look good in there - nothing stuck, nothing corroded.
*Removed ALL electrical connections, contact-cleaned and di-electric greased all of it!
* Added a nice, heavy-gauge ground-strap from the battery negative to the charging-components (over on the left under the seat and cover).
*Completed a valve-adjustment.
* Removed (for now) the stamped-steel air-intake box cover.

Here's what is happening now:
1) The bike fired right up, idles pretty smooth on-choke, but as she warms and I decrease and (eventually eliminate) all choke-input, the idle is not as smooth as one of these bikes could be.

2) As I roll-on the throttle under acceleration, she lags/bogs a bit - almost as-if there is now plenty of air in and plenty of air going out, but not enough fuel - makes sense, right? It's smooth - nt a sudden bog or anything - just feels low on power!

3) The new V&H pipes have started to turn at the exhaust port - a nice bronze-gold colour; not so much for cylinder #3 as for #1 and #4, but basically good enough. NOT AT ALL for cylinder # 2 though! It is still brand new and shiny chrome! The pipe on #2 gets hot right away on cold start-up (so it's working), but probably not as well as the other three.

When we pinch-off the fuel vacuum tube from the petcock, the idle pics up. I also see a light puff of blue smoke at idle (and perhaps while riding - not too sure).

Cyl. # 3 is probably OK - the pipe colour for # 3 is minimally different from #1 and #4. It probably has some carbon or something from when the #2 and #3 coil was bad intermittently and should clean up with time. It's #2 that concerns me!

4) Plug from #2 is black and sooty and not nice and clean like the others; I've moved it to the # 4 cylinder for now.

What ails us guys!? Please advize.

[mike_of_bbg]

Check your petcock vacuum line for gas. If there's a hole in the diaphragm it could send fuel down that way and cause rich running on #2. Recommended fix is new petcock; only moderate success reported with rebuilds.

[BassCliff]

Hi,

You've done a lot of good work so far.

You say you "serviced" the carbs? What exactly does that mean? Does it mean The Carb Rebuild Series kind of service with a set of O-rings from http://cycleorings.com? Sometimes you just have to clean the carbs properly. But I do agree that your #2 cylinder problem is probably the petcock.

Have the carbs been re-jetted for the V&H pipes? Do you still have the stock airbox installed?


Thank you for your indulgence,

BassCliff

[JungleJustice]

Yeah, after putting some miles on it again today, I'm not liking what I see here...

There is VERY little discoloration of the pipe on #3, NONE on #2 and PLENTY on numbers 1 & 4... Almost as if it was the coil for 2 & 3 not working, but the stock coils and wires did the same and now I have brand new Dyna green coils and Dyna plug-wires on there and 2&3 are acting up!

Ignition?

What module where is the ignition-potion responsible for 2&3?

By carbs serviced I mean, removed, striped-down to the lowest possible components, every single screw removed, carb-cleaner forced through there, everything polished and cleaned and inspected, every drilled channel blasted through with carb-cleaner and compressed air, jets, seats, everything taken out and cleaned!

If it is not the coils bugging 2&3 then what - where/what is the ignition module in the line for those two cylinders?

[JungleJustice]

Anybody...???

[Wingnut1]

Maybe these will help, but at least you are not alone

http://www.thegsresources.com/_forum/showthread.php?t=159284

http://www.thegsresources.com/_forum/showthread.php?t=158829

[JungleJustice]

Thanks! Yah - not fuel-related - too much of a coincidence with 2 & 3 both having an issue BEFORE and AFTER total replacement of all components down-stream from the ignition unit!

Again, are there 2 ignition-modules - one for each coil - or is there a single unit with two drivers that needs to be replaced?

[BassCliff]

Hi,

Maybe this will help.

Testing The Ignition System


Thank you for your indulgence,

BassCliff

[Dave8338]

Thanks! Yah - not fuel-related - too much of a coincidence with 2 & 3 both having an issue BEFORE and AFTER total replacement of all components down-stream from the ignition unit!

Again, are there 2 ignition-modules - one for each coil - or is there a single unit with two drivers that needs to be replaced?

It IS fuel related.

#2 plug being black and sooty is a sign of TOO MUCH fuel. When you pinch off the vac line for the petcock you say that the idle picks up. It will do this as you are leaning out the fuel mixture from a leaking petcock vac diaphragm IMHO. The fact that the header pipe is not turning color (though you say it gets hot on start up with the choke) is an additional sign of a rich fuel/air mix. Which would also explain the black sooty stock pipe, on #2 and #3.

Are your intake rubbers / runners new? All clamps replaced?

Did you use the highest possible RPM method when setting the air screws? If so...where are they set? I'm not convinced that your carbs are clean yet...

Did you pollish and then clean the carbs OR the other way around?

[JungleJustice]

Thanks guys!

Dave, I'd like to hear more about the "highest possible RPM method" please...

Any way - wiring - something was up. I followed BassCliff's step by step and some things are coming together. We have had ALL of the electrical connections on this bike out, cleaned, cleaned again and then cleaned again - dielectric grease etc etc. That stuff is good on nice new connectors, but I am not convinced that it is best on old connections. I've seen instances on my Alfas where I clean that stuff out and now the connections work better!

We did a compression-check and things were nice and even. (Two was a bit washed down, but a drop of oil and a second test had them all even at 145/145/145/150 - cold-cold and with the throttle closed by the way - shoulda been open in retrospect...)

So, weak spark on 3 & 4 - the 2 cylinders that were discoloring were actually the two with problems! You could clearly see it with the plugs out and plugged into the leads (under cranking...) Any way - connections to and from the ignition module in and out, in and out and we even used jumpers to reverse the connections to the coils! That did NOT move the weak spark to the other two plugs conclusively by the way... Ran through all of the voltage and resistance tests and then when the connections all came back together and we made some other small changes, the spark is even again between the 4! So, something is up - electrically (other than the vacuum/petcock line issue that should in theory only have effected #2, no)? But, it is great for now.

There is fuel in the vacuum-line, so we blocked it off at the carb (and set the petcock to prime to always flow - just as a test)! Fuel was dripping from that vacuum connection at the tank, so I have a new petcock coming. I also eliminated the fuel-filter for now - just as a test. I fired it up and she runs GREAT! Much smoother... Especially the low-end was GREATLY improved!

[BassCliff]

Hi,

I found this on some guy's website.

Plug Chops-Highest RPM Methods
(by Mr. tkent02 and Mr. psyguy)


Thank you for your indulgence,

BassCliff

[sackman]

Interesting post here. I thought I would pass on what I did on my honda when I ran into a simular problem with the petcock. I removed the factory vaccuum hose from my bike and plugged the line off at the petcock. Then I removed the fitting to the carb boot and replaced it with the correct size machine screw. Runs like a champ now! Cost? Nothing!

[JungleJustice]

Interesting post here. I thought I would pass on what I did on my honda when I ran into a simular problem with the petcock. I removed the factory vaccuum hose from my bike and plugged the line off at the petcock. Then I removed the fitting to the carb boot and replaced it with the correct size machine screw. Runs like a champ now! Cost? Nothing!

Yes - and this is how I am running the bike now however, you now also had to turn the petcock to prime (with fuel constantly running and no longer vacuum-actuated), which is how a billion older bikes run, but still - not proper.

When you get a float stuck for example the thing will just GUSH fuel out. Side-stand parking will sometimes also encourage a good flow...